the pump cavitates ( its an FX1)
and the little 61x motor goes from 1000rpm-7000 in a split second.
Ill try and find a video of it, you can hear the rpms hitting the top and dropping, hitting the top, and dropping.
it is VERY annoying.
if you arent hitting your limiter with a stock engine, you need more pipe, more compression, or a lower pitched impeller most likely.
My 650 boats were turning well over 7200 rpms also.
stock rev limiter on them was even worse ( 6500 I think)